In another odd twist, the index opened Monday at 2,346.98. That is being interpreted as 23rd anniversary of the June 4, 1989 crackdown when read from right to left.

Public discussion of the Tiananmen crackdown, which the Communist Party branded a "counter-revolutionary riot", remains taboo. Analysts refused to comment on the numbers.

On the popular Sina microblog site, searches using 'June 4', '64.89', 'stock market', and 'benchmark Shanghai Composite Index' were all blocked.

Such searches draw the response: "According to law such words cannot be shown."

In Beijing, the anniversary passed without any major sign of protest. The front page of the party newspaper, People's Daily, trumpeted the "Stable, fast development of the Chinese economy: Advancing to be the World's No.2".

The melee as soldiers fought their way into Beijing to clear Tiananmen Square is believed to have left hundreds dead. In response to the violence in the capital, demonstrations erupted in more than 180 cities.

Foreign Ministry spokesman Liu Weimin objected to a US State Department call for a reconsideration of the party's stance as "rude interference in China's internal affairs".

In the semi-autonomous Chinese city of Hong Kong, tens of thousands crowded into a large park to mark the anniversary. They held aloft white candles that transformed the area of soccer pitches into a sea of light, before observing a minute of silence.